It is commonly said that tall people look thinner. Here, we asked whether an illusion exists such that the taller of two equally wide stimuli looks thinner, and conversely whether the thinner of two equally tall stimuli looks taller. In five experiments, participants judged the horizontal or vertical extents of two identical bodies, rectangles, or cylinders that differed only in their vertical or horizontal extents. Our results confirmed the folk wisdom that being tall makes you look thinner. We similarly found that being thin makes you look taller, although this effect was less pronounced. The same illusion was present for filled rectangles and cylinders, but it was consistently stronger for both photographs and silhouettes of the human body, raising the question of why the human form should be more prone to this illusion.